1. Field of the Invention
This invention relates to carton opening features. Such structures of this type, generally, utilize a straight line sealing method and a lid/tray assembly having a specified corner radius wherein the carton can be easily opened at the specified corner.
2. Description of the Related Art
It is known, in the paperboard carton industry, to make use of a paperboard package which requires that the lid be constructed in a manner which allows it to be heat sealed to the tray. Exemplary of such prior art are U.S. Pat. No. 2,973,087 ('087) to H. A. Rohdin, entitled "Easy Opening Blister Pack" and U.S. Pat. No. 3,863,832 ('832) to R. L. Gordon et al., entitled "Food Container". While the lids described in these references have a pre-applied adhesive which provides for "self-venting" and "easy opening", the lid requires a separate process beyond printing to manufacture. Consequently, a more advantageous carton opening feature would be presented if the lid could be more economically manufactured and sealed to pressed paper or plastic trays without modification of straight line sealing equipment.
It is also known, to employ a tray/lid assembly that requires the lid to be sealed to the tray via a hot melt or cold adhesive. Exemplary of such prior art are U.S. Pat. No. 4,955,530 ('530) to W. R. Rigby et al., entitled "Easy Opening Lid for Ovenable Cartons" and U.S. Pat. No. 5,516,035 ('035) to J. L. Stone, entitled "Tray-Lid Assembly". While these tray/lid assemblies adequately seal the lid to the tray, the opening feature of these tray/lid assemblies requires a 100% seal around the flange of the tray to function properly. Consequently, a still further advantageous carton opening feature would be presented if the opening feature eliminated the 100% seal around the flange of the tray.
It is apparent from the above that there exists a need in the art for a tray/lid assembly which has a carton opening feature and which can be economically applied to paper or plastic trays, but which at the same time avoids the use of a 100% seal around the flange of the tray while using conventional straight line sealing methods. It is a purpose of this invention to fulfill this and other needs in the art in a manner more apparent to the skilled artisan once given the following disclosure.